November 25th, 2014
F-Open shooter Kenny Adams has enjoyed a spectacular 2013-14 season. Over the past 12 months “King Kenny” enjoyed a string of successes that established Adams as the man to beat in the ultra-competitive F-Open ranks. After finishing second at the 2013 F-Class Nationals, Kenny won the 2013 World Championship. He then won a series of regional matches heading into the 2014 National Championship. There he finished on the podium with a 3rd Place finish in the individual competition. He then earned gold as a member of the winning 4-man F-Open squad, Team Grizzly. We don’t think any other F-Open pilot has put together a stronger season.
Kenny attributes his success to great team-mates, great equipment, and great ammo. He’s a huge fan of Berger’s 7mm hybrid bullets: “The [Berger] 7mm 180 hybrids have made load testing much easier, and needless to say, raised my scores considerably!” Kenny also gave credit to his gunsmith: “I want to thank my gunsmith, Stick Starks from S&S — he got me going in this thing in the right direction four and a half years ago. Working with Stick has probably shaved a couple of YEARS off my learning curve.” Kenny’s world-championship rifle features a Panda F-Class action, Krieger barrel, and a Robertson F-Class stock. Kenny likes this combo so much he actually owns four complete red rifles with similar configurations. Check them out:
Kenny pushes those 180gr hybrids with the 7mm Remington SAUM (RSAUM) cartridge. A “new-generation” magnum, the RSAUM resembles a 6mm BR Norma on steroids. It has the same short, fat appearance, just scaled up — way up. This gives the 7mm RSAU the capacity to drive the big Berger 180-grainers at optimal velocities. The image below shows the older Berger 180gr VLD. Kenny shoots the newer 180gr Hybrid. They are both very, very accurate.
Banner Year for King Kenny
Pictured above is Kenny Adams holding his 1st Place Plaque from the 2013 F-Class World Championship. To the right, Ken (with fellow Team Grizzly members) is pictured at the 2014 F-Class Nationals accepting the Berger Trophy for the First Place F-Open 4-Man Team.
Below are Kenny Adams’s major shooting accomplishments from the past 12 months:
2013 – F-Class Nationals – 2nd Place F-Open.
2013 – F-Class World Championship – 1st Place F-Open.
2013 – Christmas Match in Florida – 1st Place F-Open.
2014 – Southwest Nationals – 1st Place F-Open 4-Man Team Grizzly (Set National record).
2014 – Orange Blossom Regional – 1st Place F-Open.
2014 – Sinclair East Coast Fullbore Nationals – 1st Place F-Open and set new Fullbore national record.
2014 – Mid West Palma – 1st Place F-Open 1200 yd. match and set 1200 yd. record.
2014 – F-Class Nationals – 3rd Place F-Open.
2014 – F-Class Nationals – 1st Place F-Open 4-Man Team – Shooter on Team Grizzly.
Kenny’s World-Beating 7mm RSAUM Load
For his 7mm RSAUMs Kenny loads Hodgdon H4350 powder and Federal 215m primers into Nosler or Norma RSAUM brass. In the RSAUM he runs Berger 180gr Hybrid bullets seated “just touching” the lands. Kenny is very precise with his charge weights. Using a Sartorius Magnetic Force Restoration scale, Kenny tries to hold his powder charges to within 1-2 kernels charge-weight consistency.
When you get it all correct, when every phase of the reloading process has been carried out perfectly, then you have rounds that can set records and win world titles. So what does championship-grade ammo look like? Take a look at the photo above. This is the 7mm RSAUM ammunition used by Kenny Adams at the 2014 Berger Southwest Nationals (SWN). Kenny is the 2013 F-Class World Champion.
Share the post "King Kenny and the Rise of the 7mm RSAUM"
November 23rd, 2014
The .308 Winchester, a shortened version of the .30-06, has almost completely replaced the .30-06 in NRA competition. The .308 is required for Palma shooting, so it is also used by many Palma competitors in other long-range and mid-range prone matches. However, with the exception of M1 Garand matches, you won’t see many .30-06 rifles on the firing lines. Does that mean the .30-06 is obsolete? Is the .308 Win really much more accurate? Or does it just offer the advantages of reduced recoil and reduced powder consumption?
Cartridge photos courtesy Deuce45s.com, a leading source of specialized military cartridges.
In his Sibling Rivalry: .308 vs. .30-06 article on the Rifleman’s Journal website, German Salazar argues that the .30-06 remains a viable competition cartridge, particularly for the long-range game. This isn’t just a subjective opinion. German has data to back up the argument that the .30-06 can still do the job.
German compares the actual scores produced by his .308 Win rifles with the scores from his .30-06 rifles. German analyzes scores, over a two-year period, shot by “matched pair” rifles (one in each caliber) with similar actions, stocks, sights, and barrels. For comparison purposes, German also includes score data from his 6XC, a modern low-recoil chambering.
RESULTS: .308 Has Small Edge at Middle Distance, But .30-06 Is Better at Long Range
Surprisingly, the .30-06 performed nearly as well as the .308 at middle distances. The .30-06 delivered 99.2% of max possible scores vs. 99.5% for the .308 Win. Notably, at 1000 yards, the .30-06 racked up 97.7% of max scores vs. 97.3% for the .308 Win. So, at 1000 yards, the .30-06 actually proved superior to the .308 Win. German explains: “This isn’t too surprising when one considers [the .308's] limited case capacity for the bullet weights typically used in Long-Range shooting. They just run out of steam and dip perilously close to the transonic range as they approach 1000 yards of flight. The extra 150 fps or so that can be safely obtained from the .30-06 case really pays off at 1000 yards.”
In NRA Mid-Range matches (500 and 600 yards), the average score and percentage of possible score for each cartridge was as follows:
.308 – 597-36X (99.5%), 960 rounds fired
6XC – 596-35X (99.3%),1260 rounds fired
.30-06 – 595-31X (99.2%), 2580 rounds fired
If we look at the score averages, the .308 comes out on top at the Mid-Range distances… by 0.3% of the possible score. By the way, notice that the 6XC, as good as it is, simply straddles the .30 caliber cartridges; it is not the winner.
German rarely shoots the .308 in matches that are only 1000 yards; most of his 1000-yard .308 shooting is done in Palma matches which include 800, 900 and 1000 yards. To make the comparison useful, the Long-Range results are presented only as a percentage of the possible score and the 800- and 900-yard stages of Palma matches were NOT included.
In NRA Long-Range and Palma matches, the average percentage of possible score for each cartridge at 1000 yards was as follows:
6XC – 98.9%, 360 rounds fired
.30-06 – 97.7%, 460 rounds fired
.308 – 97.3%, 490 rounds fired
Editor’s Note: Among the three cartridges German studied, the 6XC actually proved best at 1000 yards, delivering 98.9% of the maximum possible scores. The .30-06 was second-best with 97.7%, slightly better than the .308 Win at 97.3%.
You’ll want to read German’s full Sibling Rivalry article, which includes an interesting history of the .30-06 and .308 in High Power shooting, along with tables showing German’s actual scores with his .30-06, .308 Win, and 6XC rifles. German’s story first ran in 2011.
Share the post "Match Results for .308 Win vs. .30-06 — Surprising Findings"
November 22nd, 2014
Book by Michael Bussard (edited by S.P. Fjestad)
If you’re a serious shooter, the latest 5th Edition of the Ammo Encyclopedia (released in August, 2014), belongs in your library. This 1008-page book is probably the most comprehensive and up-to-date book in print covering current and obsolete cartridges and shotshells. Bussard’s Ammo Encyclopedia is a massive resource work. The 5th Edition now boasts 105 chapters, covering thousands of handgun, rifle, and shotgun cartridges from the past century and a half.
One of the best features is a 12-page color section depicting actual size drawings of 265 current rimfire/centerfire cartridges and shotshells. You won’t find that many “life-size” cartridge drawings in one place even on the internet. Cartridge profiles and ballistic charts have been expanded to include all new factory cartridges. The authors have even included air rifle pellets and historical images and charts. Softcover, 1008 pages.
|Comments from guys who bought the book:
“This book contains a vast array of information on many modern and even obsolete ammunition. Definately recommend for any modern reloader novice or experienced.” – Duggaboy460
“It’s a great reference book for individuals who reload their own ammunition. There is a lot more info in this Edition. Everyone who likes this information should have it in their library.” – Reloader
“I like the general and technical comments that are available for each and every cartridge. Information that predicts if a cartridge will stay in production for many more years or rapidly become obsolete.” – RSL1
Share the post "Fifth Edition of Ammo Encyclopedia Now Available"
November 19th, 2014
Many shooters, particular those who shoot vintage military rifle matches, reload once-fired military cartridge brass. This brass may be high-quality and stout, but you may encounter a primer crimp* that interferes with the seating of a new primer. There are a variety of dedicated, military-crimp tools on the market, such as Dillon’s excellent Super Swage 600 tool that “rolls the crimp away”. But the Dillon tool costs $100.95 and takes quite a bit of room on your reloading bench. If you don’t want to drop a C-note and give up valuable bench space — here’s another (much cheaper) solution.
If you already have a Wilson case trimmer set-up, you can ream away those military crimps using an affordable Wilson accessory — the Primer Pocket Reamer (large #PPR-210, small #PPR-175). This $32.99 accessory is used in conjunction with a Wilson case trimmer and case-holder as shown below.
On his Riflemans Journal website, German Salazar shows how to use the Wilson primer pocket reamer to remove military crimps on Lake City .30-06 cartridge brass. German explains: “The case goes into the Wilson case-holder, the same one used for case trimming, and the reamer replaces the trimmer head in the tool base. The threaded rod on the left side, which is normally used to regulate trim length has no use for this operation and it is simply backed out. Hold the case-holder as you turn the reamer into the primer pocket, it cuts easily and quickly. The reamer will stop cutting when the proper depth is reached.”
Do you really need to do this operation with military-crimped brass? Yes. German cautions: “any attempt to prime the case without removing the crimp will simply result in a mangled primer that cannot be expected to fire and certainly won’t fire reliably.”
Read Full Article on Riflemans’ Journal Website (more photos and detailed write-up).
*Why does military brass has a primer crimp? German answers: “The crimp is nothing more than an intentional deformation of the case around the primer pocket, the purpose of which is to retain the primer in the case despite high pressure situations in machine guns and other automatic weapons where a loose primer may cause a malfunction. As reloaders, our task is to get rid of the remnants of the crimp in order to allow re-priming the case.”
Share the post "Remove Military Primer Crimp with Wilson Primer Pocket Reamer"
November 17th, 2014
Sierra Bullets has released Version 7 of its respected Infinity Exterior Ballistics software, available now for $39.95 for Windows computers. Renowned Sierra Ballistic Consultants Ted Almgren and Dr. Bill McDonald, who have written all Sierra Software since 1970, also wrote Infinity Version 7. Both are retired scientists from a major aerospace company. Infinity Exterior Ballistics Software version 7 is a sophisticated solver that can output multiple trajectory charts. A built-in database includes bullets and cartridges offered by 15 manufacturers, both U.S. and foreign.
This 13-minute Video Demonstrates the Many Features of Infinity 7 Ballistics Software:
This sophisticated program computes the effects on the bullet trajectory of variations in firing conditions. For example, you can change altitude of the firing point, target angle (uphill/downhill), wind speeds, or even modify the Ballistic Coefficient. In fact, you can change any inputted firing condition or combination of conditions.
One very handy function is the “back-to-zero” calculation. Infinity 7 software will compute where your gun is zeroed if you know that it shoots high by a measured amount at a known range.
Compare Trajectories with Five Different Bullets
One very powerful feature of Infinity 7 is its trajectory comparison capability. With most ballistics programs (such as the JBM online ballistics calculator), you can only view one bullet’s trajectory (and associated drop chart) at a time. Not so with Infinity 7. This software handles up to five different bullets at a time. You can compare downrange velocity, energy, drop, bullet path height, or crosswind drift with results shown in bolt tabular and graphical format. That helps you select the best bullet for your gun and application. The ability to compare downrange ballistics of five different bullets at once is particularly helpful for hunters, who can compare the “hitting power” of different projectiles at various distances.
You can purchase Infinity 7 Ballistics Software as a standalone product for $39.99, or you can buy the Infinity 7 Suite for $59.95, which includes the Sierra Bullets 5th Edition Reloading Manual on CD-ROM. If you prefer a printed loading Manual, a combo pack with Infinity 7 software CD-ROM plus published (hard-back) Reloading Manual is offered for $64.95.
Share the post "Sierra Infinity 7 Ballistics Software — Video Shows Features"
November 15th, 2014
How much can you save reloading your own ammo? Well that depends on the cost of components and how much you have invested in your reloading gear. UltimateReloader.com has created a handy online Reloading Costs Calculator that lets you quickly compare the cost of reloaded ammo vs. factory ammo. Just enter the costs of powder, primers, bullets, and brass, and the Calculator will tell you the cost per round, per 20-rd box, per 50-rd box, and cost per thousand. Note — when setting the price of the brass you need to divide the initial cost by the number of predicted reloads. For example if you have 500 pieces of brass that cost $40/100 to buy ($200 total), but you get 8 reloads per case, then you put $25.00 in the Calculator ($200 total brass cost divided by 8).
True Reloading Cost Should Include Amortized Tool Expenses
Ah… but there is a catch. To understand the true cost of reloading, you also need to consider the costs of your tools and accessories, amortized over the tools’ loading lifespan. Let’s say you have $1000.00 invested in presses, dies, tumblers, measuring tools and other accessories, with a residual value of $500.00 (upon resale). If you load 5,000 rounds with those tools over their lifespan, you need to add $0.10 per round for tooling costs (your investment minus residual value, divided by the number of rounds loaded). The UltimateReloader.com Calculator does not include amortized tooling costs, but that’s something you can easily figure out on your own.
Excellent Resource for Reloading Videos
After you’ve tried out the Reloading Costs Calculator, check out the other content on UltimateReloader.com. This site features some of the best gun-related “how-to” videos on the internet. With sharp video and clear audio, the production quality is very high. If you use a progressive press (Dillon, Hornady, RCBS), you should definitely watch UltimateReloader.com’s videos — you’ll probably learn a new trick or two. In the sample video below, you can see how Hornady’s new Bullet Feeder works with its Lock-N-Load Progressive press.
Share the post "UltimateReloader.com Reloading Cost Calculator"
November 14th, 2014
Gear Review by German Salazar
This article originally appeared in German Salazar’s Rifleman’s Journal website.
Many of you have doubtlessly read Bryan Litz’s articles in our Daily Bulletin and on his Applied Ballistics website about various current long-range bullets. Bryan’s work carries a great deal of weight in the world of ballistics, so his comments (and mathematical proofs) regarding the benefits of bullet pointing certainly caught my attention. Bullet pointing, like meplat trimming, is an effort to reduce the ballistic inconsistency created by the somewhat jagged tip of the jacket where the bullet forming dies bring it to a point in the manufacturing process. Of course, we could eliminate this problem altogether by shooting closed-tip, open-base bullets like the Lapua D46, but that merely shifts the jacket problem to the other end of the bullet.
In any event, hollow point bullets rule the accuracy world today, so John Whidden, multi-time National Long Range Champion at Camp Perry and a talented gunsmith and designer to boot, came up with a very handy tool to let us make those hollow points pointier. Let’s have a look at John’s tool and see how it works.
The Whidden Bullet Pointing Die System uses a Forster bullet seating die body as its basic structure and that’s a good choice given the quality machining Forster does on these. The real heart of the tool comes in two parts: the caliber sleeve and the pointing die that fits inside the sleeve. In fact, to point up different caliber bullets, you only need to change the caliber sleeve, everything else remains the same. The last item is the bullet base that slips into a standard .308 shellholder and supports the bullet as it goes into the die body.
It took me less than five minutes to get everything set up, including changing the caliber sleeve from 6mm to .30 caliber. John’s instruction sheets are well illustrated and clearly written; you should have no problem getting up and running.
Pointing the bullets is as easy as sizing a piece of brass. You can see in the top photo the difference between a few pointed bullets and a few un-pointed ones. The innermost pointed bullet in the picture was my first attempt and I adjusted the die a little after that, you can see that the others are closed a little more. John even includes a couple of sample bullets so that you can see one done right and one done wrong. That is a nice addition that can help you achieve the desired results.
I think Bryan’s work supports the validity of this concept and John’s tool puts it into practice in a simple-to-use manner that makes it just about impossible to do any damage to the bullet. I have shot pointed bullets in various calibers at many matches now. Pointing is not a “miracle cure”, but I believe that pointing bullet tips can produce long-range accuracy gains, through reduced vertical dispersion, for many popular types of match bullets. The Whidden Bullet Pointing Die System retails for $220.00 (with one insert). Additional die inserts are $42.00 each. Extra caliber sleeves are also $42.00. You can purchase directly from Whidden Gunworks, or from Sinclair International.
Share the post "Whidden Gunworks Bullet Pointing Die System"
November 9th, 2014
“22 Plinkster” is an avid shooter who has produced a number of entertaining videos for his YouTube Channel. In the video below, he tackles the question “Why Do Misfires Occur in .22 LR Rimfire Ammunition?” This is the most common question posed to 22 Plinkster by his many viewers. He identifies four main issues that can cause .22 LR misfires or faulty ignition:
1. Damaged Firing Pin — The dry firing process can actually blunt or shorten the firing pin, particularly with older rimfire firearms. Use of snap caps is recommended.
2. Poor Ammunition — Some cheap brands have poor quality control. 22 Plinkster recommends using ammo from a manufacturer with high quality control standards, such as CCI and Federal.
3. Age of Ammunition — Rimfire ammo can function well for a decade or more. However the “shelf life” of rimfire ammunition is not infinite. You ammo’s “lifespan” will be shortened by heat, moisture, and humidity. You should store your rimfire ammo in a cool, dry place.
4. Mishandling of Ammunition — Tossing around ammunition can cause problems. Rough handling can cause the priming compound to be dislodged from the rim. This causes misfires.
Image courtesy Cheaper Than Dirt Shooters Log.
Share the post "How to Avoid Misfires with .22 LR Rimfire Ammunition"
November 3rd, 2014
Applied Ballistics has just announced Ballistic Performance of Rifle Bullets. This new book is chock full of “mission critical” data on hundreds of popular projectiles. This latest reference book from Bryan Litz contains live fire test data on 400 modern rifle bullets. The data pages contained in this book are similar to the 225 bullet data pages found in Applied Ballistics for Long Range Shooting. The Ballistic Coefficient data is based on live fire testing methods which are repeatable within +/- 1%. If you’re looking for “rock-solid” info on the ballistic performance of today’s most popular rifle projectiles, this work is the definitive print resource. Scroll down to see a sample page from the new book.
CLICK HERE to see the full list of bullets covered in this new resource book.
Visit the Applied Ballistics Online Store to pre-order your copy and save $5. Note: Pre-orders are expected to ship and arrive at USA destinations in time for Christmas. Retail price is $54.95, with a $5.00 pre-order discount.
More about the Book
“Modern rifles have reached an unprecedented level of accuracy. In many cases, the weak link in the chain of hitting targets is the trajectory modeling, which is based on bullet performance,” stated author Bryan Litz. Unfortunately, shooters can’t always rely on advertised Ballistic Coefficients (BCs) being accurate. Slight errors in BC modeling can be the cause of missing your target. Furthermore, a meaningful apples-to-apples comparison of bullet performance is not possible when the BCs are determined differently by various brands.
This book provides highly accurate ballistic performance data for 400 modern long range bullets from .224 to .408 caliber. By employing a common testing method for bullets of all brands, shooters are provided with consistent and accurate performance data which can be used to compare and select bullets, as well as to calculate accurate trajectories which put your shots on target at long range. It is claimed that the BC data is accurate (and repeatable) to +/- 1% for all bullets tested.
Detailed stability data is also included which can be used to determine suitable twist rates for bullets in various environments.
View Sample Page from Ballistic Performance of Rifle Bullets:
NOTE: This is a reference book which contains mostly data pages. There is a single chapter in the beginning which talks about how to use the data. For a more thorough understanding of the science of external ballistics, readers are referred to: Applied Ballistics for Long Range Shooting (2d Edition).
Share the post "New Applied Ballistics Book Features Test Data for 400 Bullets"
October 31st, 2014
NEW PRODUCT REPORT by Dennis Santiago
At the recent Western CMP Games and Creedmoor Cup Matches in Phoenix, I received a box of the all-new .30-06 Match-Grade ammunition from Dennis DeMille of Creedmoor Sports. My job was to test the ammo (at the Games) and write about it. This box was part of Creedmoor’s 3-million-round production run for the Civilian Marksmanship Program (CMP). CLICK HERE for Ammo Sales.
Author Dennis Santiago (right) with Dennis Demille of Creedmoor Sports (left).
The new .30-06 “Match-Grade” ammunition from Creedmoor is impressive. This ammo is made from top-quality components: brand new Lapua .30-06 brass and 167gr Lapua Scenar bullets. The ammo, optimized for 200-yard CMP Games tournaments, runs at 2720 fps. DeMille says the Standard Deviation (SD) is very tight with this ammo — comparable with precision hand loads. The low SD reflects great attention to detail in ammo assembly. Creedmoor’s industrial loader is run at half-speed to improve consistency. Charges are thrown precisely — I believe in two (2) half-charges.
When you hold the ammunition up to the light, each round appears a perfect clone of each other round — something that cannot be said for some other factory ammo (even so-called “match ammo”). This is about a close as one is likely to get to a precision hand load. The good news is that Creedmoor plans to produce similar ammunition in other chamberings.
The economics of the ammunition are equally intriguing. This ammo is being sold by the CMP for $1.30 per round. Think about that — new .30-06 Lapua brass sells for around $100.00 per hundred cases. So, you get to fire a precision match round for about 30 cents and have premier once-fired brass for future use. The price per rounds tells me that CMP isn’t making money on this — it is being sold at near cost to promote marksmanship.
Great Ammo at a Great Price
In offering this new .30-06 ammo at an affordable price, the CMP is making it possible for non-reloading competitors to have the same quality of ammunition as those who handload with premium components. This will be a major improvement for shooters of m1903s and M1 Garands. I think this ammo can be real equalizer for those who do not currently hand-load their own .30-06 ammunition. The CMP and Creedmoor Sports are to be commended for collaborating on this game-changing product introduction.
Where to get the Creedmoor Sports CMP .30-06 Ammo
The CMP is now selling the Creedmoor-produced .30-06 ammo on the CMP website, item #4C3006CS167-100 (click the “e-Store” button to launch shopping cart). The retail price is $130.00 per 100-round case (i.e. two boxes). That works out to $1.30 per round.*
.30-06 Ammo Performance
When someone hands you a box of ammo with a challenge how can you not throw all your match plans out the door and play? I was planning to fire the CMP GSM match with my M-1 Garand the next day using 150gr SMK handloads but I said, “What the heck. Let’s go for it.” You get five sighters in a GSM match which is plenty to zero with new ammo.
The ammo is optimized for shooting 200-yd CMP matches with rifles like my as-issued DCM M-1 Garand.
I shoot the M-1 Garand matches with a rebuilt 5-digit receiver gun with a 1950s barrel refurbished at Anniston Armory that I got from the DCM back in the day when the postman delivered them. It shoots true and has garnered its share of Western Games trinkets over the years including a number of golds and one of those coveted M-1 EIC 4 points medals. It’s a good platform for the test. Sighters revealed the Creedmoor ammo shoots about two minutes higher impact versus my pet load. The tale of the tape said 96-2X slow prone, 93-1X rapid prone and 81-1X offhand totaling 270-4X. The DCM machine took home a bronze in 2014.
Accuracy and Consistency
This Creedmoor ammo is indeed amazingly consistent. The slow prone stage was a pure joy to shoot. This ammunition is “brutally honest”. It will reveal every little error you make be it defocusing on your front sight drenching in sweat under the Phoenix sun, not being fast enough to reset your NPA mid-string in your rapid as the big gun moves you around or just being jittery on your feet during the back half of your offhand. With this ammo I felt confident to trust that any error was mine after each shot. There was no wondering about the ammo. I knew its feedback was accurate. That is a huge thing to be that confident in one’s gun and ammunition. I never felt that confident with HXP or even my handloads. If anything, I now know that even my ammo for the M1 Garand and M1903A3 will benefit from the same careful case preparation and assembly as my tactical rifle or long range ammo.
*At the Western CMP Games this Creedmoor .30-06 ammo was sold at a discounted price of $1.15 per round. That’s an example of the great deals one can get by attending CMP competitions.
Share the post "CMP Offers High-Quality .30-06 Ammo from Creedmoor Sports"
October 29th, 2014
Chances are that many of you have packed away your ammo and shooting supplies for the winter. Maybe you put your brass in a storage bin that might also contain solvents, old rags, or used bore swabs. Well, if you use any ammonia-based solvents, we suggest you separate the brass and ammo and keep it away from potential ammonia vapors. This is because long-term exposure to ammonia fumes can cause cracks to form in your brass. This can lead to case ruptures and possible injury.
This case-cracking phenomenon has been called Season Cracking, a form of stress-corrosion cracking of brass cartridge cases. Season cracking is characterized by deep brittle cracks which penetrate into affected components. If the cracks reach a critical size, the component can suddenly fracture, sometimes with disastrous results. If the concentration of ammonia is very high, then corrosion is much more severe, and damage over all exposed surfaces occurs. The brass cracking is caused by a reaction between ammonia and copper that forms the cuprammonium ion, Cu(NH3)4, a chemical complex which is water-soluble. The problem of cracking can also occur in copper and copper alloys such as bronze.
Season Cracking was originally observed by the British forces in India a century ago. During the monsoon season, military activity was reduced, and ammunition was stored in stables until the dry weather returned. Many brass cartridges were subsequently found to be cracked, especially where the case was crimped to the bullet. In 1921, in the Journal of the Institute of Metals, the phenomenon was explained by Moor, Beckinsale, and Mallinson. Apparently ammonia from horse urine, combined with the residual stress in the cold-drawn metal of the cartridges, was responsible for the cracking.
Don’t store ammunition (or brass) for long periods in a box or container holding ammoniated solvents:
The Australia Department of Defense (AUSDOD) has also explored the problem of brass cracking caused, at least in part, by exposure to ammonia. A study was done to see whether the amount of cracking (from ammonia exposure) varied according to the duration and temperature of the annealing process used on the brass. CLICK HERE to read AUSDOD Research Report.
Story idea from Boyd Allen. We welcome reader submissions.
Share the post "Tech Tip: Don’t Store Brass and Ammo Near Ammonia Solvents"
October 28th, 2014
In discussions of ballistics, you’ll see references to “tangent” and “secant” bullet shapes. We know that, for many readers, these terms can be confusing. To add to the confusion, bullet makers don’t always identify their projectiles as secant or tangent designs. This article provides a basic explanation of tangent and secant designs, to help you understand the characteristics of both bullet shapes.
Tangent vs. Secant vs. Hybrid
Most match bullets produced today use a tangent ogive profile, but the modern VLD-style bullets employ a secant profile. To further complicate matters, the latest generation of “Hybrid” projectiles from Berger Bullets feature a blended secant + tangent profile to combine the best qualities of both nose shapes. The secant section provides reduced drag, while the tangent section makes the bullet easier to tune, i.e. less sensitive to bullet seating depth position.
Berger Bullets ballistician Bryan Litz explains tangent and secant bullet ogive designs in a glossary section of his Applied Ballistics website, which we reprint below. Bryan then explains how tangent and secant profiles can be combined in a “hybrid” design.
How Bullet Ogive Curves are Defined
While the term “ogive” is often used to describe the particular point on the bullet where the curve reaches full bullet diameter, in fact the “ogive” properly refers to the entire curve of the bullet from the tip to the full-diameter straight section — the shank. Understanding then, that the ogive is a curve, how is that curve described?
LITZ: The ogive of a bullet is usually characterized by the length of its radius. This radius is often given in calibers instead of inches. For example, an 8 ogive 6mm bullet has an ogive that is a segment of a circular arc with a radius of 8*.243 = 1.952”. A .30-caliber bullet with an 8 ogive will be proportionally the same as the 8 ogive 6mm bullet, but the actual radius will be 2.464” for the .30 caliber bullet.
For a given nose length, if an ogive is perfectly tangent, it will have a very specific radius. Any radius longer than that will cause the ogive to be secant. Secant ogives can range from very mild (short radius) to very aggressive (long radius). The drag of a secant ogive is minimized when its radius is twice as long as a tangent ogive radius. In other words, if a tangent ogive has an 8 caliber radius, then the longest practical secant ogive radius is 16 calibers long for a given nose length.”
Ogive Metrics and Rt/R Ratio
LITZ: There is a number that’s used to quantify how secant an ogive is. The metric is known as the Rt/R ratio and it’s the ratio of the tangent ogive radius to the actual ogive radius for a given bullet. In the above example, the 16 caliber ogive would have an Rt/R ratio of 0.5. The number 0.5 is therefore the lowest practical value for the Rt/R ratio, and represents the minimum drag ogive for a given length. An ogive that’s perfectly tangent will have an Rt/R ratio of 1.0. Most ogives are in between an Rt/R of 1.0 and 0.5. The dimensioned drawings at the end of my Applied Ballistics book provide the bullets ogive radius in calibers, as well as the Rt/R ratio. In short, the Rt/R ratio is simply a measure of how secant an ogive is. 1.0 is not secant at all, 0.5 is as secant as it gets.
Hybrid Bullet Design — Best of Both Worlds?
Bryan Litz has developed a number of modern “Hybrid” design bullets for Berger. The objective of Bryan’s design work has been to achieve a very low drag design that is also “not finicky”. Normal (non-hybrid) secant designs, such as the Berger 105gr VLD, deliver very impressive BC values, but the bullets can be sensitive to seating depth. Montana’s Tom Mousel has set world records with the Berger 105gr VLD in his 6mm Dasher, but he tells us “seating depth is critical to the best accuracy”. Tom says a mere .003″ seating depth change “makes a difference”. In an effort to produce more forgiving high-BC bullets, Bryan Litz developed the hybrid tangent/secant bullet shape.
Bryan Litz Explains Hybrid Design and Optimal Hybrid Seating Depths
Story sourced by Edlongrange.
Share the post "Ogive No Jive — Litz Explains Tangent, Secant, and Hybrid Ogives"